Primer



Nov. 14, 1967 G. R. ECKSTEIN' PRIMER Filed NOV. 30, 1965 Inventor: George R Eckstein 4. N Qmfl w. y

Attorneys United States Patent 3,352,240 PRIMER George R. Eckstein, Fairfield, Conn., assignor to Remington Arms Company, Inc., Bridgeport, Conn., a corporation of Delaware Filed Nov. 30, 1965, Ser. No. 510,508 5 Claims. (Cl. 10245) ABSTRACT OF THE DISCLOSURE A unitary battery cup-anvil assembly for small arms ammunition having a partially pre-sheared flap portion on the anvil which is adapted to hinge open to provide a definable and controllable flash hole opening after firing but which is substantially imperforate before firing.

This invention relates to an improved battery type primer having improved non-mass detonating characteristics. More specifically, the invention relates to a unitary battery cup-anvil assembly having a partially pre-shaped portion adapted to hinge open to provide a flash hole means whereby the flame of the ignited priming mixture can be carried to the main propellant charge in the shotshell.

There have been various attempts to provide hermetically sealed primers including various patents which have issued in the past. The reasons for a hermetically sealed primer have been discussed in other patents and need not be discussed fully here. Briefly, most attempts have been designed to seal the priming mixture from moisture and foreign particles, such as dust and propellant powder. The priming mixture must also be prevented from dusting out of the primer.

It must be pointed out that the present invention does not contemplate a perfectly sealed primer which is impervious to air flow or moisture although such a primer can be achieved. Instead, it has been discovered that a slight leakage in the primer is desirable for several reasons. First, in electroplating battery cups, in order to achieve satisfactory results, it is desirable that the plating bath make contact with the inner surfaces of the battery cup. When the battery cup bottom is completely airtight, air becomes trapped in the bottom of the battery cup and the plating bath cannot reach all portions of the cup consistently. With a slight leak present, air can leak out and the bath can flow into the cup to fill the bottom more consistently.

Secondly, present practice calls for the insertion of the charged primer cup into the battery cup while the primer cup is still Wet with shellac. This is a safety precaution but it is imperative that the alcohol vapors be removed from within the battery cup during the drying cycle. The slight leak in the conical or angular wall of the battery cupanvil assembly will permit the drying of the primer even though the drying cycle may be longer.

Another advantage of the present invention is that the volume of the primer ignition chamber in which the priming mix is confined and ultimately ignited is substantially less than the volume of the conventional battery cup arrangement wherein a flash hole is provided in the front transverse end of the cylindrical battery cup. This decrease in chamber volume permits the use of less weight of priming mix to achieve the necessary ballistics to fire the propellant powder. Thus, the present improved primer requires less priming mix to achieve the same results. Ballistics under cold-temperature conditions are much improved so that this advantage alon may be sufliciently important to justify use of the improved primer.

Another advantage is that a one-piece battery cup-anvil separate battery cup and anvil elements.

- Another advantage in the present primer is that the closed flash hole flap prevents explosive priming mix from dusting out of the primer after it has been charged as Well as eliminating static electricity hazards.

A further important advantage is that the closed flash hole construction permits the use of fine grain propellant powder without having the fine powders sift into the battery cup through the open flash hole. The presence of fine propellant within the battery cup is objectionable because the ignition of the powder within the relatively confined area of the battery cup may cause excessive pressure and blow the primer cup rearwardly away from the battery cup. This advantage is particularly important in the design of certain loads where very fine propellant powder is desirable but which heretofore has not been possible because of the problem of the powder sifting back through the flash holes into the battery cup. Furthermore, hand reloaders appear to favor fine-grained propellant powders.

A primary advantage of the present invention is increased safety. Thus, experiments have definitely shown that a substantial advantage is present in the ability of the present primer to reduce or eliminate mass detonation of primers when packed in bulk. By mass detonation it is meant the almost instantaneous, chain-reaction type of explosion which is caused when one primer is ignited and it in turn ignites adjacent primers, etc. The absence of primer flash holes through which the flame of an adjacent, accidentally-ignited primer can enter results in a very real safety feature. This obviously results in safer primer manufacturing as well as permitting bulk packing of primers to facilitate inter-plant and commercial shipping'and storing of primers. 1

At present, there are various legal limitations on storage, handling, and transportation of primers, based mainly on whether the primers will mass-detonate. For example, present primer packaging requires special partitioning in order to prevent the flash from one primer from getting into direct contact with the primer mix of adjacent primers. If the flash from one primer can enter through the flash hole of another primer to ignite the priming mix therein, the speed of the primers being ignited is such that it is substantially instantaneous with the result that an explosion occurs. If capable of being mass-detonated, the primers are classified as hazardous explosives and must be handled as such during shipment. If the primers cannot be mass-detonated, handling and shipping precautions may be less strict since they are no more hazardous than small arms ammunition.

It is an object of this invention to provide an improved primer which is economical to make and safe to handle.

Itis another object of this invention to provide an improved battery cup-anvil assembly having hinged flask hole cover means thereon which remains substantially closed before firing and which hinges open and remains in one piece with the battery cup-anvil assembly after firing.

It is another object of this invention to provide an improved battery cup-anvil assembly having hinged flask cover relationship which permits more or less breathing of air through the closed flash hole means while still retaining the safety features of preventing primer massdetonation.

Other objects will be apparent from the scription taken in connection drawings in which:

FIGURE 1 shows a cross-sectional view of a shotshell showing a battery cup-type primer incorporating the present invention;

following de- With the accompanying FIGURE 2 shows a cut-away view of the improved primer; and

FIGURE 3 shows a cross-sectional view of the improved battery cup-anvil assembly before firing.

Referring to the drawing, FIGURE 1 shows a shotgun cartridge in which the body casing 12 is preferably made of plastic although paper or any other suitable material can be used. The lower or rear end portion of the body 12 has a basewad 14 positioned therein and is closed off with a metal head 16, the rear end of which is flanged at 18 and then is turned inwardly to form a tranverse face 20. The transverse head face 20 and basewad 14 have central openings therein into which the primer 22 is inserted. Propellant means 24 is positioned within the shotshell adjacent the basewad and the primer.

The foregoing describes a conventional shotshell and applicants invention resides in the improved primer 22.

The improved primer 22 includes a battery cup 24 having a tubular portion 26 with an outwardly directed flange 28 at its rear end and a front end which turns inwardly and then rearwardly to form an anvil portion 30 integral with the battery cup 24. The anvil portion 30 includes a forward tubular support portion 32 which is spaced inwardly from and substantially parallel to the forward end of the battery cup 24 to form a recess 34 therewith.

A conical wall portion 36 extends from support portion 32 and converges rearwardly to a centrally located anvil impact end 38. Anvil impact end 38 abuts against sensitive priming mix 40 which is positioned within the bight of a primer cup 42 which in turn is inserted into the rear open end of the battery cup to form a primer ignition chamber 43 therewith. It can be seen from FIGURE 2 that the forward open end 44 of the primer cup 42 extends into the recess 34 formed by the forward ends of the battery cup and anvil portion.

Positioned in the conical portion 36 of the anvil portion 30 is a flash hole cover or flap 46 which has been presheared along three sides 48a, 48b, 48c as shown in FIGURE 2, while remaining intact at the upper end 48d. It should be appreciated that the specific configuration of the flap 46 is not critical and it can be made in the form of a triangle, circle, etc., as well as being hinged on the sides or bottom of the flap.

It can be seen that some of the propellant powder 24 will be confined within the cavity formed by the outside of the anvil portion adjacent to said flap 46. Upon ignition of the priming mix 40, the flash hole cover 46 is blown out away from the conical wall member to form an effective flash hole while still remaining hinged and intact along unsheared portion 48d.

It will be appreciated that there are several features in the one-piece construction of the battery cup-anvil assembly which can be varied to change the ballistics. Thus, the area, thickness, and shape of the flap 46 can be varied to require more or less pressure to open the flap. The configuration of the anvil impact end 38 can be varied to give more sensitivity and the primer ignition chamber 43 can also be varied to provide more or less confinement to the priming mix when it is fired, thus varying the pressure and heat developed within the primer chamber.

The one-piece battery cup-anvil assembly 22 is formed preferably from steel, such as SAE 1010 which can develop an ultimate strength of about 55,000 p.s.i. to about 100,000 p.s.i. in the ranges of cold work that is used in making the improved one-piece battery-anvil assembly. This range of ultimate strengths is above the range of cast materials of practical cost. Since the flash hole cover or flap must be substantially imperforate while permitting limited quantities of solvent vapor or air to move through, the method of forming the partially pre-sheared flap is to lance out the flap and then move it back into abutting relationship with the conical wall portion as is shown in FIGURE 3. The control of the critical dimensions and,

more important, the necessary ductility, would not be present with die casting methods.

The diameter of the battery cup is limited by requirements that the primers be interchangeable among the various companys products and that it ignite propellants under adverse conditions such as very low temperatures. These requirements call for a certain range of primer mix weight in a range of battery cup diameters. The weight of primer mix confined in a range of possible chamber volumes will result in predetermined pressures which must be absorbed by the permissible thickness of battery cup material. Without the necessary strength, the front portion of the battery-anvil assembly will blow off or crack when fired in the shotshell. By using a die cast primer, these portions must be made thicker in order to prevent rupture and this extra thickness cuts down on the amount of priming mix possible. The ultimate strength of the material thus is important in this combination since it assures that practical dimensions for outside diameter and cup base can be attained.

What is claimed is:

1. In a cartridge having a rear head end adapted to receive a primer in a conventional manner, said primer comprising a one-piece battery cup and anvil member insertable in said cartridge head, said one-piece member comprising a tubular battery cup portion having its rear end open ended and adapted to receive a primer cup in substantially hermetically sealed relationship, an elongated anvil portion integrally formed with the forward extremity of said battery cup portion and projecting rearwardly towards said open end of said battery cup portion, said anvil portion comprising a support wall spaced inwardly from the forward extremity of said battery cup portion and forming an annular recess therewith, an inclined wall portion integrally formed with said anvil support wall which converges rearwardly into an anvil impact end which is substantially centrally located within said battery cup portion adjacent the open end of said battery cup portion, a primer cup having sensitive priming mixture therein inserted into the open end of said battery cup portion, and flash hole blow-out means on said inclined wall portion, said flash hole blow-out means comprising a definable unitary flash hole cover portion which is pre-sheared along the major portion of its periphery and whose peripheral minor portion is integral with the inclined Wall portion, the inclined wall portion and the flash hole cover portion forming a substantially imperforate closed end wall which permits air to move therethrough while preventing priming mixture and propellant powder from passing through prior to firing, said partially pre-sheared flash hole cover adapted to hinge outwardly about said unsheared minor portion to form an accurate and definable flash hole opening upon firing of the primer.

2. In a cartridge as recited in claim 1 wherein said onepiece battery cup and anvil is formed from a metallic material which will develop over about 55,000 p.s.i. ultimate strength.

3. In a cartridge having a rear head end adapted to receive a primer in a conventional manner, the combination of a charged primer cup and a tubular battery cup having an open end at its rear into which the charged primer cup is inserted, said tubular battery cup having its forward end substantially closed off by an anvil means which is integrally formed with the forward end of said battery cup, said anvil means having a conical portion which converges rearwardly to form an anvil impact end adjacent said charged primer cup, a definable unitary flash hole cover in said conical portion having a major portion of its periphery pre-sheared and a minor portion of its periphery unsheared and integrally connected to said conical portion, said flash hole cover being in substantial abutting relationship with said conical portion to form a substantially imperforate wall therewith, said flash hole cover being adapted to hinge outwardly about said unsheared minor portion upon ignition of said primer charge to form an accurate and definable flash hole openmg.

4. In a cartridge as recited in claim 3 wherein said battery cup is fabricated from metallic material which will develop over about 55,000 p.s.i. ultimate strength.

5. In a cartridge as recited in claim 3 wherein said anvil means comprises a forward tubular portion which is integral with and inwardly spaced from the forward end of said battery cup thus forming an annular recess therewith, said conical portion being integral with the rear end of said anvil tubular portion and converging rearwardly therefrom, said annular recess adapted to receive the forward end of said charged primer cup.

References Cited FOREIGN PATENTS 628,995 11/1961 Italy.

SAMUEL FEINBERG, Primary Examiner. ROBERT F. STAHL, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,352,240 November 14, 1967 George R. Eckstein It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 71, for "alon" read alone column 2, line 55, for "flask" read flash line 61, strike out "battery cup anvil assembly having hinged flask" and insert instead primer having a controllable flash hole and Signed and sealed this 8th day of April 1969.

(SEAL) Attest:

Edward M. Fletcher, J r. EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. IN A CARTRIDGE HAVING A REAR HEAD END ADAPTED TO RECEIVE A PRIMER IN A CONVENTIONAL MANNER, SAID PRIMER COMPRISING A ONE-PIECE BATTERY CUP AND ANVIL MEMBER INSERTABLE IN SAID CARTRIDGE HEAD, SAID ONE-PIECE MEMBER COMPRISING A TUBULAR BATTERY CUP PORTION HAVING ITS REAR END OPEN ENDED AND ADAPTED TO RECEIVE A PRIMER CUP IN SUBSTANTIALLY HERMETICALLY SEALED RELATIONSHIP, AN ELONGATED ANVIL PORTION INTEGRALLY FORMED WITH THE FORWARD EXTREMITY OF SAID BATTERY CUP PORTION AND PROJECTING REARWARDLY TOWARDS SAID OPEN END OF SAID BATTERY CUP PORTION, SAID ANVIL PORTION COMPRISING A SUPPORT WALL SPACED INWARDLY FROM THE FORWARD EXTREMITY OF SAID BATTERY CUP PORTION AND FORMING AN ANNULAR RECESS THEREWITH, AN INCLINED WALL PORTION INTEGRALLY FORMED WITH SAID ANVIL SUPPORT WALL WHICH CONVERGES REARWARDLY INTO A ANVIL IMPACT END WHICH IS SUBSTANTIALLY CENTRALLY LOCATED WITHIN SAID BATTERY CUP PORTION ADJACENT THE OPEN END OF SAID BATTERY CUP PORTION, A PRIMER CUP HAVING SENSITIVE PRIMING MIXTURE THEREIN INSERTED INTO THE OPEN END OF SAID BATTERY CUP PORTION, AND FLASH HOLE BLOW-OUT MEANS ON SAID INCLINED WALL PORTION, SAID FLASH HOLE BLOW-OUT MEANS 